Components

Membrane 3x4 Matrix Keypad + extras

PC-00123

Adafruit Industries

$3.64 tax incl.

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Punch in your secret key into this numeric matrix keypad.

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Punch in your secret key into this numeric matrix keypad. This keypad has 12 buttons, arranged in a telephone-line 3x4 grid. It's made of a thin, flexible membrane material with an adhesive backing (just remove the paper) so you can attach it to nearly anything. The keys are connected into a matrix, so you only need 7 microcontroller pins (3-columns and 4-rows) to scan through the pad. Check the tutorials tab for links to an Arduino library and example code. 

We include a 7-pin extra-long header strip so you can plug this into a breadboard with ease.

  • Weight: 7.5 grams
  • Keypad dimensions: 70mm x 77mm x 1mm (2.75" x 3" x 0.035")
  • Length of cable + connector: 85mm
  • 7-pin 0.1" pitch connector



There is a very nice Matrix Keypad Arduino library that works great with this item. The only thing we suggest is to change the initialization code in the examples to this:

#include 

const byte ROWS = 4; //four rows
const byte COLS = 3; //three columns
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {8, 7, 6, 5}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {4, 3, 2}; //connect to the column pinouts of the keypad

Keypad keypad = Keypad( makeKeymap(keys), rowPins, colPins, ROWS, COLS );

This will swap the * and # keys and also let you connect to the Arduino to match this image

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Membrane 3x4 Matrix Keypad + extras

Membrane 3x4 Matrix Keypad + extras

Punch in your secret key into this numeric matrix keypad.